Avalanche Forecast

Archived

Mar 29th, 2023–Mar 30th, 2023

Alpine

Natural avalanches unlikely.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Northwest Coastal, Kitimat, Nass, Rupert, Seven Sisters, Shames, Stewart, Howson.

Increasing cloud, cooler temperatures and wind are expected to keep the snow surface cooler on Thursday than previous days. Still carefully consider your exposure if you find the snow surface to be moist or wet.

Confidence

Moderate

Avalanche Summary

Most avalanche activity this week has been limited to small (size 1) wet loose.

However, a few outliers - large slab avalanches - have been reported throughout the region. Although we don't think we have a widespread problem at this point, it's something to keep in mind as the spring warms up. On Monday south of Terrace, a size 2.5 wet slab was reported out of a steep, rocky start zone on a northwest aspect around treeline. On Tuesday, a couple of large avalanches (size 2.5-3) with deep crowns were observed in the alpine north of Stewart. These are suspected to have been cornice-triggered and to have run on a weak layer buried in January that hasn't otherwise shown reactivity for several weeks.

Other natural cornice failures have been observed, not triggering slabs on slopes below.

Snowpack Summary

Moist snow or a crust exists on the surface on all aspects below treeline and on steep south facing slopes treeline and above. Dry snow can be found on shady aspects at upper elevations, wind-affected and well-settled.

The lower snowpack is well consolidated and strong.

Weather Summary

Wednesday night

Clear. Light variable wind. Alpine low -4 °C. Freezing level 1500 m dropping to valley bottom.

Thursday

Increasing cloud. Wind increasing to moderate southwest. Alpine high -2 °C. Freezing level 1000 m.

Friday

8-15 cm of new snow. Strong southwest wind. Alpine high -4 °C. Freezing level 900 m.

Saturday

Around 5 cm overnight then clearing to a mix of sun and cloud. Light southwest wind. Alpine high -5 °C. Freezing level 800 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
Watch for unstable snow on specific terrain features, especially when the snow is moist or wet.
A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
Avoid exposure to slopes that have cornices overhead.

Problems

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.